Pneumatic transducer

ABSTRACT

An elongated cylinder having an axially extending rod projecting from one end and adapted for attachment to a tool such as a punch or the like. A massive piston in the cylinder and slidable on the rod is forced by air pressure into impactive engagement with a collar anvil mounted on the rod. The force of impact drives the rod longitudinally to operate the tool and valves control the air for reciprocating the piston to and from its initial, latched position. The striking faces of the piston and anvil are tapered to avoid damage from the forces of impact.

0 ilmted States atent [151 3,638,739 Burke Feb. 1, 1972 [54] PNEUMATIC TRANSDUCER 2,374,019 4/1945 Kahler et a1 ..l73/114 X o [7'2] Inventor: Gordon 11. Burke, 61 15 Noland Road, 91/73 Shawnee Kans 66203 m [22] Filed: June 2, 1970 Primary Examiner-David H. Brown Attorney-Don M. Bradley [21] App1.No.: 42,814

[57] ABSTRACT [52] 11.8. C1 ..l73/114, 173/131, 173/ 1 37, An elongated cylinder having an axially extending rod project- 91/313, 92/ 16 ing from one end and adapted for attachment to a tool such as [51] Int. Cl ..B25d 9/00, 1221c 3/00 a punch or the like. A massive piston in the cylinder and slida- Field f fllh 173/114, 131, 132, 133, 137, ble on the rod is forced by air pressure into impactive engage- 173/ 139; 91/313, 1142;92/16, 27, 23 ment with a collar anvil mounted on the rod. The force of impact drives the rod longitudinally to operate the tool and 5 References Ciied valves control the air for reciprocating the piston to and from its initial, latched position. The striking faces of the piston and UNITED STATES PATENTS anvil are tapered to avoid damage from the forces of impact. 1,740,713 12/ l 929 Rundgrist 173/137 12 Claims, 7 Drawing Figures n M l PATENTED FEB 11972 3,638,739

Afforrvsy PATENTEU FEB 1 1972 SHEET 2 OF 2 INVENTOR. Gordon H. Bur/ 5 PNEUMATIC TRANSDUCER This invention relates to energy converters, and more particularly to a transducer capable of imparting substantial forces over relatively short distances such as is often required for operation of tools such as metal punches or the like.

Fluid-operated drivers for punches are not new. However, in the past, most such devices utilized relatively high fluid pressures for generating the forces necessary for pushing the punch through the material. These punches required relatively strong, usually C-shaped frames capable of withstanding the forces imparted between the punch driver and the frame. Such frames were quite heavy and added materially to the expense of the units. They also rendered such tools relatively unportable.

It is, therefore, the primary object of this invention to pro- I the invention are to provide a work producing energy converter which is capable of substantially automatic operation, can be relatively economically fabricated and which requires little maintenance in operation. Another very important object of the present invention is to provide in such a converter or driver mutually engageable components configured to minimize damage to the components resulting from their impact. These and other objects of the invention will be further explained or will become apparent from the claims, specification and drawings.

In the drawings:

FIGS. 1a and 1b are fragmentary, vertical, cross-sectional views taken longitudinally of a transducer embodying the principles of this invention, and together showing substantially the entire transducer, parts being broken away and shown in cross section to shorten the illustration;

FIG. 2 is an enlarged, fragmentary, vertical, cross-sectional view of the trigger mechanism in its unlatching position;

FIG. 3 is a vertical cross-sectional view taken along line 3- 3 of FIG. lb;

FIG. 4 is a vertical cross-sectional view taken along line 4 4 of FIG. 1b;

FIG. 5 is a fragmentary, side elevational view on a reduced scale illustrating the transducer, the operating and control system being shown diagrammatically; and

FIG. 6 is an enlarged, perspective view of the trigger plunger.

The transducer or impact driver embodying the principles of this invention is broadly designated in FIGS. la, lb and 5 by the reference numeral 10. Driver 10 includes an elongated, transversely circular cylinder 12 closed at its lowermost end by a head 14. The proximal end of cylinder 12 telescopes into head 14 as shown in FIG. 1b, and a seal 16 prevents flow of fluid by the connection between cylinder 12 and 14.

A short, transversely circular collar 18 is interposed in cylinder 12 proximal the uppermost end of the latter. Collar I8 has a laterally extending projection 20 providing the housing for a trigger mechanism broadly designated 22. The uppermost end of cylinder 12 is closed with a plug 24. The ends of cylinder sections telescoped into collar 18 are sealed against fluid flow by seals 26 and 28 while the upper end of cylinder 12 is sealed to plug 24 by sea] 30.

An elongated, transversely circular rigid rod 32 extends axially of cylinder 12. Rod 32 comprises a plurality of sections, and the lowermost section 34 is rigidly secured to the intermediate section 36 by means of a massive anvil in the form of a collar 38 threadably engaged with the proximal ends of rod sections 34 and 36 respectively.

It should be noted that collar 38 is sufficiently small in diameter that it is capable of moving from cylinder 12 into the axially extending bore of head 14. A bushing 40 guides the projecting rod section 34 and a washer 42 telescoped over rod section 34 is disposed as an abutment to prevent engagement of the anvil collar 38 with the end of head 14. To this end, washer 42 may be made of a semiyieldable material such as plastic or the like for absorbing the force of any impact of anvil 38 against the washer.

The upper end of the intermediate rod section 36 is coupled with an upper section 44 by a collar 46. Section 44 is guided by a bushing 48 received in an axial bore of plug 24. Section 44 extends upwardly or to the left as shown in FIG. la beyond plug 24 and passes through a housing 50 containing a helical spring 52 and a washer 54 as shown in the drawing. A portion 56 of rod section 44 projects outwardly beyond the end of housing 50 and into an axial bore 58 of a cap 60. Portion 56 is of reduced diameter from portion 62 in housing 50. Portion 62 .is, itself, of smaller diameter than section 44 so that washer 54 is carried by the rod as the latter moves to the left as viewed in FIGS. Ia and lb. Washer 54 bears against spring 52 compressing the latter during such movement.

A segment 64 of portion 56 in bore 58 is further reduced in diameter and has a pair of sloping shoulders 66 and 68 defining the end terminals of segment 64. The actuator 70 of a three-way valve 72 projects into bore 58 proximal segment 64 and in position to be engaged by the shoulders 66 or 68 for operating the valve as will be more fully explained hereinafter.

A massive hammer in the nature of a piston 74 is slidably telescoped over rod 32 in cylinder 12. Piston 74 has a pair of integral outwardly extending annular bands 76 and 78 proximal the upper and lower ends of the piston. Bands 76 and 78 are relatively close fitting with the interior wall of cylinder I2 so that the latter is divided by piston 74 into a lower chamber 80 and an upper chamber 82. A port 84 in head 14 communicates with chamber 80 and chamber 82 is in fluid communication with a port 86 in plug 24 by means of a conduit 88.

The lowermost end of piston 74 is tapered inwardly at a shoulder 90. The striking surface 92 of the piston is concave and is adapted to complementally engage the tapered convex proximal face 94 of the anvil collar 38. The axially extending bore 96 of piston 74 is enlarged near the nose portion of the piston as at 98 (FIG. 1b).

The uppermost end of piston 74 carries an integral hook 100 comprising a portion 102 of piston 74 of reduced diameter and containing an annular groove 104 presenting a shoulder I06 extending perpendicularly to the axis of rod 32. A tapered shoulder 108 defines the other side of groove I04.

Mechanism 22 includes a plunger broadly designated 110 (FIG. 6) having nose portion 112 configured as shown clearly in FIG. 6 to present an upwardly facing shoulder I14 adapted to complementally engage shoulder 106 of hook 100 for holding piston 74 in longitudinally spaced relationship from anvil 38. Plunger 110 has a radially extending piston lI6 carrying an annular seal I18 and adapted for reciprocation within the bore of housing 20. Piston I16 divides bore 120 into a pair of compartments as the piston moves longitudinally of bore 120 as will be more fully explained hereinafter.

Plunger 110 has an axially extending bore 122 which contains a helical spring 124 and an end plug 126 extending inwardly of bore 122. A central aperture in plug 126 receives a tubular projection 128 rigidly mounted to a closure I30 disposed to close the bore I20 of housing 20. A valve member 132 carried on the end of spring 124 normally engages plug 126 to close the inwardly projecting end thereof when plunger 110 is in the position illustrated in FIG. la with the nose of the plunger projecting inwardly into cylinder 12. Displacement of the plunger rearwardly to the position illustrated in FIG. 2 slides plug 126 back on the plunger to break the sealing contact between the inwardly projecting end of plug 126 and valve member 132. This permits passage of fluid in bore 122 past valve member 132, into the tubular projection 128, through a channel 134 in the base of plug I26 and thence out a conduit I36 to atmosphere. On the other hand, when plunger 110 is in the position illustrated in FIG. Ia, valve member 132 is seated across the opening of plug 126 to prevent the flow of fluid in bore 122 to atmosphere. An opening 138 extending radially through plunger I10 communicates bore 122 with the housing bore 120. The latter communicated with chamber 82 upstream of piston 116 by means of a conduit 140.

Bore 120 is communicated by a conduit 142 with a port 144 which is adapted to be coupled with a source of pressurized fluid such as compressed air or the like which may be contained in a tank 146 (FIG.

Referring now to FIG. 5, means for controlling the operation of driver comprises a spring centered, normally closed three-way valve 148 having outlet ports 150, 152 and 153, and an inlet port 154, the latter being adapted for coupling with a line 156 communicating with a source of pressurized fluid. A line 158 from line 156 communicates with a pilot port 160 of valve 148 through the three-way pilot valve 72. Valve 72 has an outlet port 162 for communicating port 160 with atmosphere when valve 72 is in its normally closed position.

A line 164 communicates between line 156 and the other pilot port 166 of valve 148 through a three-way pilot valve 168. Valve 168 may be manually operated and is normally closed with a port 170 for communicating port 166 of valve 148 to atmosphere when the pilot valve is in its normal condition.

In operation, the work produced by transducer or driver 10 is available at the projecting end of rod section 34. For example, a punch may be affixed to the external threads 172 on the rod section. Piston 74 is held in spaced relationship from the anvil collar 38 by the projecting end of plunger 110. To this end, shoulder 114 engages with shoulder 106 of the piston as shown in FIG. 1a. The air pressure from tank 146 in the compartment of bore 120 behind the plunger piston 116 biases the plunger into its latching position for holding piston 74 in this position. It will at once be apparent to those skilled in the art that a spring could be used to provide this biasing force mechanically.

The operator of the driver manually opens valve 168 to introduce air to valve 148 for shifting the valve member 174 thereof to the left as viewed in FIG. 5. Air pressure from line 156 is thereby introduced into chamber 82 through port 86 which is coupled to valve 148 by a line 176. At the same time, chamber 80 of cylinder 12 is vented through line 178 and port 153 valve 148 to atmosphere. Valve member 174 is readily shifted to this initial position under the influence of the compressed air from line 156 since valve 72 is in its closed position and the opposite side of valve 148 is vented to atmosphere.

The air introduced to chamber 82 acts against piston 116 to initiate a rearward movement for the plunger. It is contemplated that the pressure of the air in line 156 will be substantially greater than the pressure in tank 146, the latter serving merely as a control pressure for biasing the plunger toward its latched position.

The rearward movement of plunger 110 forces valve member 132 off its seat over plug 126. This results in the venting of the air pressure in the housing bore 120 to atmosphere through opening 138, valve member 132, channel 134 and conduit 136. It will be understood that member 132 has a longitudinal groove 180 for flow of fluid past the member. Similarly, a notch 182 in the projecting end of tube 128 introduces the fluid into the tube.

The venting of the air pressure behind the plunger piston 116 permits rapid acceleration of the plunger rearwardly and away from the piston 74 under the full force of the air pressure in chamber 82. This releases plunger 110 from its latching condition with cylinder 74 to permit the latter to be accelerated along rod 32 toward the anvil collar 38. The spacing between the initial position for piston 74 and anvil collar 38 is chosen so that maximum benefit may be derived from the acceleration of the piston prior to its impact with the anvil. It is contemplated that approximately lOO pounds per square inch of air pressure will be introduced into chamber 82 and that the spacing chosen will permit approximately 35 pounds of air pressure to remain in the chamber at the time of impact of the piston against the anvil. These parameters provide about the optimum work output from the driver.

The impact drives anvil collar 38 to the right as viewed in FIG. lb. This, in turn, drives the rod section 34 and any tool affixed thereto in a corresponding direction.

While a variety of sizes and weights of the respective members could be utilized, it has been found that satisfactory results can be obtained wherein such values are chosen which will provide approximately 1,780, foot pounds of work to be developed as a result of the impact. Assuming that the tool driven by driver 10 is to move a total of approximately 96-inch, the force of impact may be in the magnitude of approximately 84,960 pounds. The control pressure in tank 146 which has been successfully utilized with driver 10 is on the order of approximately 10 p.s.i.

The force of impact which carried rod 32 to the right as viewed in FIGS. la and lb brings shoulder 66 of segment 64 into engagement with the operator 70 for valve 72. This operates the valve to introduce pressure from line 56 into the opposite end of valve 148, port 166 of the latter having been vented to atmosphere by valve 168 having returned to its normally closed position.

Pressurized air from line 156 is now introduced into chamber and line 176 is vented to atmosphere. This forces cylinder 74 back to its original position. The tapered face 184 on plunger opposite shoulder 114 is capable of sliding along the tapered trailing edge 186 of piston 74 to retract the plunger sufficiently for the piston to return to its initial position. The forces of impact of piston 74 on this stroke shifts rod 32 to the left as shown in FIG. la and the impact may be cushioned by spring 52. As soon as valve member 48 is permitted to return to its normal centered position as illustrated in FIG. 5, spring 52 returns the components to the position shown in FIG. 1a. This places driver 10 in condition for the next cycle of operation.

Anvil 38 is of lighter construction and therefore inherently weaker than the more massive piston 74. Face 94 of collar 38 is tapered away from the piston 74 as the outermost edge of the collar is approached. This direction of taper provides components of the forces of impact tending to hold the collar together rather than tending to split the collar apart. Such construction lends durability to the driver while permitting use of lighter and less expensive parts than would otherwise be available. The more rugged and massive construction of piston 74 permits the application of impactive forces to the oppositely flared face 92 without deleterious effects.

It is contemplated that driver 10 may be used for a variety of different applications. Manifestly, the driver would normally be mounted in a rigid frame or the like (not shown). Further, it is contemplated that regulators may be provided in any of the air lines for increasing or reducing the air pressure required for proper operation of the driver. For example, it is generally not necessary to have nearly so much air pressure applied to chamber 80 for return of the piston 74 to its latched position as is desirable for driving the piston into impactive engagement for operating the driver rod 32.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A transducer for converting pneumatic force into work comprising:

means defining a closed chamber, and including movable hammer means comprising one wall of said chamber; guide means engageable with the hammer means for reciprocal movement of the latter along the guide means responsive to pneumatic pressure in the chamber;

anvil means disposed in the path of travel of the hammer means for impactive engagement by the latter to move the anvil means;

work takeoff means operably coupled with the anvil means for movement therewith;

means for introducing pressurized air into said chamber to move the hammer means toward the anvil means; and automatic release means for holding said hammer means in spaced relationship from the anvil means until the force of said air in the chamber reaches a predetermined value,

whereby release of the hammer means under said force results in impactive forces against the anvil means to move said takeoff means.

2. The invention of claim 1, wherein is included a cylinder, the chamber being in the cylinder, and wherein said hammer means includes a piston slidable in the cylinder.

3. The invention of claim 2, wherein said piston has an axially extending bore, and wherein said guide means includes an elongated rod received through the bore, the piston being slidable on the rod for reciprocable movement along the latter into and out of engagement with the anvil means.

4. The invention of claim 3, wherein said anvil means includes a collar rigidly secured to the rod and projecting radially outwardly therefrom in disposition for engagement by the piston, and wherein said takeoff means is carried by the rod.

5. The invention of claim 4, wherein said collar has an end facing the piston, said end having a surface inclined at an angle away from the direction of the piston as the periphery of said surface is approached.

6. The invention of claim 5., wherein said piston has a face disposed to strike said collar surface, and wherein said striking face of the piston is configured to complementally engage said surface of the collar.

7. A pneumatic driver for tools comprising:

a closed cylinder;

an elongated rod extending axially in the cylinder and projecting through one end wall of the latter for longitudinal sliding movement relative to the cylinder, said projecting end of the rod being adapted for coupling to a tool;

a massive piston in the cylinder and mounted for movement along the rod, said piston dividing the cylinder into a pair of chambers;

anvil means secured to the rod and disposed in one of said chambers;

means for selectively providing pressurized air to the other latter in a standby position spaced from the anvil means and releasable when the pressure in said other chamber reaches said predetermined value, whereby the air drives said piston into impact against the anvil means to move said rod longitudinally.

8. The invention of claim 7, wherein said latch means includes a plunger having a latched position extending into the path of travel of the piston, said plunger being movable away from said latched position responsive to air pressure in said other chamber, and means normally biasing said plunger into the latched position and automatically operable to release said biasing force upon movement of the plunger responsive to said air pressure, whereby to speed the unlatching of said piston.

9. The invention of claim 8, wherein said latch means ineludes a housing having a bore, said plunger being slidable in the bore and dividing the latter into a pair of compartments, one compartment being in communication with said other chamber, and wherein said biasing means includes means providing pressurized air in the other compartment, the plunger including structure operable automatically upon movement of the plunger responsive to air pressure in said other chamber greater than air pressure in said other compartment to relieve the air pressure in the latter, whereby to speed the movement of the plunger from said latched position.

1%. The invention of claim 7, wherein is provided means for selectively providing pressurized air to said one chamber to force said piston back to its latched position.

11. The invention of claim 10, wherein the means for providing air to said one chamber includes an actuator including a component carried by the rod for movement therewith, said actuator being operably responsive to movement of the rod from impact by the piston to automatically supply air to said one chamber.

12. The invention of claim 11, wherein is provided means associated with each of said air su ply means for automatically venting one of said chambers w en pressurized air is supplied to the other chamber. 

1. A transducer for converting pneumatic force into work comprising: means defining a closed chamber, and including movable hammer means comprising one wall of said chamber; guide means engageable with the hammer means for reciprocal movement of the latter along the guide means responsive to pneumatic pressure in the chamber; anvil means disposed in the path of travel of the hammer means for impactive engagement by the latter to move the anvil means; work takeoff means operably coupled with the anvil means for movement therewith; means for introducing pressurized air into said chamber to move the hammer means toward the anvil means; and automatic release means for holding said hammer means in spaced relationship from the anvil means until the force of said air in the chamber reaches a predetermined value, whereby release of the hammer means under said force results in impactive forces against the anvil means to move said takeoff means.
 2. The invention of claim 1, wherein is included a cylinder, the chamber being in the cylinder, and wherein said hammer means includes a piston slidable in the cylinder.
 3. The invention of claim 2, wherein said piston has an axially extending bore, and wherein said guide means includes an elongated rod received through the bore, the piston being slidable on the rod for reciprocable movement along the latter into and out of engagement with the anvil means.
 4. The invention of claim 3, wherein said anvil means includes a collar rigidly secured to the rod and projecting radially outwardly therefrom in disposition for engagement by the piston, and wherein said takeoff means is carried by the rod.
 5. The invention of claim 4, wherein said collar has an end facing the piston, said end having a surface inclined at an angle away from the direction of the piston as the periphery of said surface is approached.
 6. The invention of claim 5, wherein said piston has a face disposed to strike said collar surface, and wherein said striking face of the piston is configured to complementally engage said surface of the collar.
 7. A pneumatic driver for tools comprising: a closed cylinder; an elongated rod extending axially in the cylinder and projecting through one end wall of the latter for longitudinal sliding movement relative to the cylinder, said projecting end of the rod being adapted for coupling to a tool; a massive piston in the cylinder and mounted for movement along the rod, said piston dividing the cylinder into a pair of chambers; anvil means secured to the rod and disposed in one of said chambers; means for selectively providing pressurized air to the other of said chambers for forcing said piston along the rod toward the anvil means; latch means engageable with the piston for holding the latter in a standby position spaced from tHe anvil means and releasable when the pressure in said other chamber reaches said predetermined value, whereby the air drives said piston into impact against the anvil means to move said rod longitudinally.
 8. The invention of claim 7, wherein said latch means includes a plunger having a latched position extending into the path of travel of the piston, said plunger being movable away from said latched position responsive to air pressure in said other chamber, and means normally biasing said plunger into the latched position and automatically operable to release said biasing force upon movement of the plunger responsive to said air pressure, whereby to speed the unlatching of said piston.
 9. The invention of claim 8, wherein said latch means includes a housing having a bore, said plunger being slidable in the bore and dividing the latter into a pair of compartments, one compartment being in communication with said other chamber, and wherein said biasing means includes means providing pressurized air in the other compartment, the plunger including structure operable automatically upon movement of the plunger responsive to air pressure in said other chamber greater than air pressure in said other compartment to relieve the air pressure in the latter, whereby to speed the movement of the plunger from said latched position.
 10. The invention of claim 7, wherein is provided means for selectively providing pressurized air to said one chamber to force said piston back to its latched position.
 11. The invention of claim 10, wherein the means for providing air to said one chamber includes an actuator including a component carried by the rod for movement therewith, said actuator being operably responsive to movement of the rod from impact by the piston to automatically supply air to said one chamber.
 12. The invention of claim 11, wherein is provided means associated with each of said air supply means for automatically venting one of said chambers when pressurized air is supplied to the other chamber. 